Snap switch with actuating tongue

ABSTRACT

An electrical switch having an elongated, resilient, conductive blade having upper and lower legs whose end edges are mounted in vertically spaced seats formed in a dielectric switch body. The seats are closer together than the unstressed length of the blade, and one or more terminals abut one face of the central portion of the blade and impose thereon upper and lower bows of opposite curvature. When the switch is actuated by decreasing the curvature of the upper bow, the blade snaps so that its opposite face abuts a second set of one or more terminals. The upper blade leg includes a pair of laterally spaced leg segments, joined by an upper yoke adjacent to the upper edge, and an integrally formed tongue projects downwardly from the yoke into the opening between the leg segments. Deflection of the tongue by an actuator creates stress in the yoke and leg segments tending to decrease the curvature of the upper bow and simultaneously increase the curvature of the lower bow until snap action occurs. A second identical switch is symmetrically disposed in the switch body. The blade may include a pair of laterally projecting arms midway of its length to serve as a shorting bar between laterally spaced abutment terminals. Spring means bias the actuator toward normal position, and releasable latching means maintain it in its actuated position, including a cardioid trackway formed in the actuator sidewall, the trackway being provided with a pair of vertically spaced locking indentations. A ball detent, resiliently biased partially into the trackway, is permitted to move laterally in order to follow the cardioid trackway, which is ramped to insure unidirectional movement of the ball around the trackway.

United States Patent 1 1 3,898,4Q2

Ford Aug. 5, 1975 SNAP SWITCH WITH ACTUATING end edges are mounted invertically spaced seats TONGUE formed in a dielectric switch body. Theseats are closer to ether than the unstressed len th of the [75]Inventor: ig Ford west Covma blade, am? one or more terminals abut oneface of the a l central portion of the blade and impose thereon upper[73] Assignee: Airpax Electronics Incorporated, and lower bows ofopposite curvature. When the Cambridge, Md. switch is actuated bydecreasing the curvature of the P Filed g 27 1973 upper bow, the bladesnaps so that its opposite face abuts a second set of one or moreterminals. The [Zl] Appl. No; 391,639 upper blade leg includes a pair oflaterally spaced leg segments, joined by an upper yoke adjacent to the U5 Cl 200/67 74/100 P upper edge, and an integrally formed tongueprojects [Sl] H 01h 13/36 downwardly from the k mm the Openmg between581 Field of Search 200/67 DA, 67 DB; 337/89, the leg Segments"peflecton of the tongue by 337/135 136' 74/100 P ator creates stress inthe yoke and leg segments tendmg to decrease the curvature of the upperbow and simultaneously increase the curvature of the lower [56]References cued bow until snap action occurs. A second identical UNITEDSTATES PATENTS switch is symmetrically disposed in the switch body.

2,133,309 10/1938 Schmidinger 200/67 DB The blade may include a pair oflaterally projecting 1167543 7/1939 Bflgenhflgen 200/67 DB arms midwayof its length to serve as a shorting bar 2395'698 2/1946 200/67 DBbetween laterally spaced abutment terminals. Spring 2444'529 7/1948Puster 200/67 DB means bias the actuator toward normal position, andFOREIGN PATENTS OR APPLICATIONS releasable latching means maintain it inits actuated 58.739 10/1922 Sweden 200/67 D position, including acardioid trackway formed in the Primary Examiner-David Smith, Jr.Attorney, Agent, or Firm-Miketta, Glenny, Poms & Smith 5 7 ABSTRACT Anelectrical switch having an elongated, resilient, conductive bladehaving upper and lower legs whose actuator sidewall, the trackway beingprovided with a pair of vertically spaced locking indentations. A balldetent, resiliently biased partially into the trackway, is permitted tomove laterally in order to follow the cardioid trackway, which is rampedto insure unidirectional movement of the ball around the trackway.

10 Claims, 21 Drawing Figures PATENTED AUB 5l975 SHEET PATENTED AUG 5I975 PATENTEU AUG 5 SNAP SWITCH WITH ACTUATING TONGUE BACKGROUND ANDSUMMARY OF THE INVENTION The present invention relates generally toelectrical switches, and more particularly to a switch of the snapaction type employing a switching blade of resilient conductive materialwhich is maintained under longitudinal compressive stress in the body ofthe switch whereby to impose on the blade oppositely bowed portions.which may for convenience be referred to as convex and concave bowedportions.

In a preferred form of the present invention, the resilient conductiveblade constituting the switching element in the present switch isgenerally cruciform in shape, having upper and lower legs and a pair oflaterally extending arms substantially midway of the blade. The upperleg of the blade is provided with a central opening, and an integrallyformed tongue projects downwardly into the opening. When the blade ismounted in its housing seats, a pair of abutment terminals abut thearms, and impose on the blade the oppositely bowed configurationmentioned above. A second pair of abutment terminals lies on theopposite side of the arms from the first named pair. Actuation of theswitch consists of decreasing the curvature of the upper bowed portionof the blade and simultaneously increasing the curvature of the lowerportion of the blade until a point is reached when the blade snaps fromits rest position with its arms in contact with the first pair ofabutment terminals into an actuated position with its arms in contactwith the second set of abutment terminals. Thus the arms constitute ashorting bar between the terminals of each pair. Actuation of the switchis effected by slidable abutting contact of an actuator element againstthe blade tongue, whereby stress is built up in the tongue and in theadjacent portions of the leg until the snap action results. Suchmovement of the actuator element is accomplished by depressing apushbutton in accordance with the present illustrative embodiment of theinvention.

In an alternative form of the invention, the blade arms are eliminated,one end of the blade is in electrical contact with a common terminal,and one abutment terminal is provided on either side of the blade,approximately midway of its length. The blade is otherwise the same asthe cruciform blade first above mentioned, and includes an actuatingtongue in its upper leg.

Releasable latching means are desirably provided in accordance with thepresent invention, whereby a sin gle depression of the pushbutton orotherwise actuating the actuator element. serves to maintain the switchin its actuated condition until a second depression of the pushbutton.Under these conditions the switch is of the type referred to asalternating. If the releasable latching means are omitted, then theswitch is of the momentary type, being actuated only so long as thepushbutton is maintained depressed.

A preferred form of the latching means includes a cardioid shapedtrackway formed in the sidewall of the actuator, and a ball detentelement partially received in the cardioid trackway, and retainedtherein by resilient means carried by the switch body. The trackway isprovided with two vertically spaced lock positions for the ball detent,corresponding to retracted and actuated positions of the actuatingelement. The trackway itself is suitable contoured and provided withramps to insure that the ball detent, which is permitted limited lateralmovement relative to the trackway in order to follow the cardioid path,proceeds always in the same direction around said path.

In the preferred form of the invention, a second blade and associatedabutment terminals may be provided, disposed symmetrically to the firstabout a central vertical axis of the switch, so that movement of theactuator switches two separate circuits substantially simultaneously.

It is accordingly a principal object of the present invention to provideand disclose an electrical switch having a novel conductive blade toaccomplish the switching, and releasable latching means to maintain theswitch, selectively, in either its make or break position. Other objectsand purposes are to provide, in such a switch, a blade of generallycruciform shape, having a pair of laterally extending arms constitutingin effect a shorting bar; to provide, in such a blade, an upper leghaving an opening formed therein and an integral tongue extendingdownwardly into the opening, slidably abuttable by an actuator elementduring actuation; to provide a releasable latching means to selectivelymaintain the actuator element in actuated position, and including acardioid track'way having upper and lower lock positions, in which aball detent is resiliently biased for travel around the cardioid betweenone lock position and the other; for providing in such a switch aduplicate set of switching elements and terminals by which to double thecircuit handling capacity of the switch in compact space; and for otherand additional objects as will become clear from a reading of thefollowing description of a preferred embodiment of the invention, takenin connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of aswitch embodying the present invention.

FIG. 2 is a vertical sectional view taken on line 11-11 of FIG. 1,showing the parts in their normal or rest positions.

FIG. 3 is a fragmentary sectional view similar to FIG. 2, except showingthe parts in their actuated positions.

FIG. 3A is a fragmentary sectional view similar to FIG. 3 and laterallyaligned therewith, showing the right hand portion of the switch properin actuated position as in FIG. 3, but with the pushbutton carrierretracted to its rest position.

FIG. 4 is a sectional view taken on the line IVIV of FIG. 2.

FIG. 5 is a developed view of the trackway and, in dotted outline, thesuccessive positions of the ball detent therein.

FIGS. 6a, b, c and d are successive views of the migration of the balldetent around the cardioid trackway, FIG. 6a corresponding to theposition of the switch seen in FIG. 2, FIG. 66 corresponding to theposition of the switch seen in FIG. 3, and FIGS. 6!) and 6d showing theball and trackway in intermediate positions.

FIGS. 7, 8 and 10 are sectional views taken along the arrows VIIVII,VIIIVIlI, and X-X respectively of FIG. 2.

FIG. 9 is a sectional view taken on the arrows IX-IX of FIG. 3.

FIG. 11 is a bottom plan view of the switch taken on the arrows XlXl ofFIG. 2.

FIG. 12 is a perspective view of the preferred form of blade inaccordance with the invention.

FIG. 13 is a schematic diagram showing the wiring of the severalterminals of the preferred embodiment of the invention.

FIG. 14 is a perspective view of a switch blade in accordance with analternative form of the invention.

FIG. 15 is a fragmentary sectional view of a portion of a switchincorporating the blade of FIG. 14.

FIG. 16 is a fragmentary sectional view taken on the arrows XVIXVI ofFIG. 15.

FIG. 17 is a fragmentary sectional view taken on the arrows XVIIXVII ofFIG. 15, and showing the operative portions of the switch in the leftportion of the switch assembly, including a second blade and pair ofterminals, disposed symmetrically relative to the corresponding parts inthe right half of the switch assembly.

DETAILED DESCRIPTION Referring now to the drawing, in FIG. 1 there isindicated generally at 20 a housing for containing the operativeportions of the present switch, the housing 20 being desirably made ofmetal and including an integrally formed externally threaded boss 21projecting upwardly from the housing proper, for convenience in mountingthe present switch housing on a control panel or the like. A pushbuttoncarrier 22 is telescopically received within the threaded bore 21 andextends thereabove, and is adapted to have a suitable pushbutton mountedon its upper end for actuation by the user. With continued reference toFIG. 1, the lower portion of the cylindrical wall of the housing 20 iscrimped inwardly at 23, in order to be attached to a downwardlyextending base 24 of dielectric material, from which outlet terminalsproject downwardly, there being visible in FIG. 1 a total of four suchterminals, arranged in pairs 25, 26 and 27, 28. As will be laterunderstood in detail, and as a glance at FIG. 11 will show, there aredesirably a total of eight downwardly projecting outlet terminalsdisposed symmetrically about a central vertical plane of the switch, theother four terminals being designated by primed reference numerals.

The internal construction of the elements of the switch will be bestunderstood by reference first to FIGS. 2 and 4, showing those parts intheir normal or rest positions.

Thus the lower portion of housing 20 comprises a hollow cylindricalcasing indicated generally at 30 which receives in its upper portion abody shell of dielectric material indicated generally at 32. This shellincludes an upper annular ring portion 34 and, extending downwardlytherefrom and integrally formed therewith, a pair of arcuately extendingskirts 36, 37 (see FIG. 4), interrupted by a pair of diametricallyopposed openings 38, 39, seen in FIG. 2. The lower interrupted annularedges 40 of skirts 36, 37 abut the upper face 41 of dielectric basemember 24. At the midpoint of arcuate skirts 36 and 37, body shell 32 isprovided with support columns 42 and 43 respectively, having coaxialposts 44 and 45 which extend downwardly into bores 46 and 47 formed indielectric base 24.

As will be later understood, after assembly of the switch blades withshell 32 and base 24, the lowermost ends 48 and 49 of posts 44 and 45are heat sealed or welded to adjacent portions of dielectric base 24, so

that the shell and base form an integral dielectric body containingtherewithin the operative portions of the switch, including switchblades and abutment terminals to be now described.

In FIG. 12 there is indicated generally at 50 the preferred form ofblade constituting the moving contact member in accordance with thepresent invention. Blade 50 is of generally cruciform shape, having anelongated lower leg 52 terminating downwardly in a lower edge 53 and anupper leg indicated generally at 54 terminating in an upper edge 55which is parallel to lower edge 53. Upper leg 54 is of substantiallygreater width than that of lower leg 52, and has formed therein acentral opening 56 between a pair of laterally spaced leg segments 57and 59 joined by an upper transverse yoke. An integrally formed tongue58 extends downwardly from the yoke, into the opening 56 with itssidewalls spaced inwardly from the inner walls of leg segments 57 and59, so that, as will be later understood, tongue 58 can be flexed awayfrom the plane of the yoke during operation. The blade also includes apair of arms 60, 62, extending laterally substantially midway betweenlower and upper edges 53, 55. The total crosssectional area of legsegments 57 and 59 is approximately equal to that of lower leg 52.

All of the elements of blade 50 thus far described are integrally formedof a flexible conductive material such as a sheet of copper or copperalloy. To minimize contact resistance during switch operation, as iscustomary in the switch art, contactor buttons 64 may be provided on thearms, desirably made of any of well known materials of high conductivitysuch a silver alloy or the like. As shown in FIG. 12, the outer surfacesof the contactor button 64 are desirable slightly convex.

There will now be described in connection with FIG. 2 a switch assemblycomprising the blade of FIG. 12, its mounting in the dielectric bodywithin casing 30, and the abutment terminals with which the blade armsmake contact during switch operation. As will be evident from FIG. 2,the present illustrative embodiment of the invention includes a pair ofidentical switch assemblies, disposed precisely symmetrically relativeto a central vertical plane through the switch, and for brevity only theswitching assembly in the left portion of FIG. 2 will be described indetail. Thus the body shell 32 and base 24, both of dielectric material,define therebetween an operating cavity housing the switch blade 50 andthe terminals with which the switch arms are abuttable. The lower faceof body shell 32 has formed therein a groove 72, and base 24 of thedielectric body similarly has a groove 74 formed therein. Each grooveconstitutes a seat for receiving the lower and upper edges 53, 55 ofblade 50, and the longitudinal spacing between grooves 72 and 74 isappreciably less than the distance or height between the edges 53 and 55of the blade when the blade is in its unstressed planar condition seenin FIG. 12. Blade 50 is thus forced to assume a curved configurationthroughout its length, and a pair of abutment terminals 76 and 77(compare FIG. 10) serve to impose upon blade 50 an oppositely bowedconfiguration in the upper portion of blade 50 comprising leg 54 fromthe bowed configuration in the lower portion of blade 50 comprising leg52. More specifically, and using the terms from the view point of thecentral portion of the switch, upper leg 54 assumes a convenx curvature,while lower leg 52 assumes a concave curvature. Under these conditionstongue 58 projects linearly from the yoke tangentially to leg 54, sincethe tongue is unaffected by the stress imposed upon leg 54.

It may be noted that, if the switch blades happen to assume the oppositecurvature from that just described after the dielectric body parts havebeen heat sealed together, it is a simple matter for the operator tocorrect the situation, before the dielectric body is assembled intocasing 30, by inserting a small tool through one or both of the openings38, 39 and forcing the upper bowed leg 54 to snap into properconfiguration.

In addition to abutment terminals 76, 77 mentioned above, there is alsoprovided a second pair of abutment terminals 78 and 79 disposed on theopposite side of contactor buttons 64 from abutment terminals 76, 77.Abutment terminals 76, 77 will be referred to herein as normally closedabutment terminals, while abutment terminals 78, 79 will be referred toherein as normally open terminals. It will thus be seen that the arms60, 62 of switch 50, together with their contactor buttons 64,constitute a shorting bar between the abutment terminals with which theyare in contact.

Actuator means are provided for moving the blade 50 from its restposition seen in FIG. 2 to its actuated position seen in FIG. 3. In thepresent embodiment of the invention, such actuator means include anactuator head indicated generally at 80 which is mounted centrally ofthe switch and vertically slidable between its upper position seen inFIG. 2 and a lower position seen in FIG. 3. As best seen in FIGS. 4 and9, actuator head 80 has formed in its lower periphery a pair ofdiametrically opposed guide grooves 82, 83 for slidably receiving a pairofinwardly projecting splines or lands 84, 85, respectively, whichproject radially inwardly from the otherwise cylindrical inner wall ofbody shell 32, so that the actuator head 80 is permitted non-rotationalverti cal movement between its upper and lower positions. Withcontinuing reference to FIG. 9, it will be seen that actuator head 80 isprovided with a pair of nose portions 86, 87, which are bounded byarcuately spaced recesses 88 in the lower periphery of actuator head 80.The actuator noses 86, 87 are diametrically opposed, and are disposed at90 from the axes of guide grooves 82, 83.

A comparison of FIGS. 2 and 3 will show that, as actuator head 80 ismoved downwardly by means to be described in detail hereinafter,actuator head nose 86 comes into slidable abutting contact with tongue58 of blade 50, moving the tongue arcuately about the base of the tongueas a fulcrum, and thereby building up stress in the upper leg 54,tending to decrease the curvature of that leg. A decrease of curvatureof upper leg 54 necessarily is accompanied by an increase of curvatureof lower leg 52, together with a slight downward movement of conductivebuttons 64. At some point in the downward movement of actuator 80, thestresses thus produced in blade 50 will cause the blade to snap from itsposition of FIG. 2, in contact with normally closed abutment terminals76, 77, into its position seen in FIG. 3, with the conductive buttons incontact with normally open terminals 78, 79.

It is to be particularly noted that the recesses 88 on either side ofactuator nose 86 insure that actuator nose 86 touches only tongue 58 inits downward movement, and does not touch the upper leg 54 proper. In aswitch of the present type. having a blade under longitudinalcompressive stress and forming oppositely bowed curved portions, it isnecessary to make certain that actuation of the switch from its restposition to its actuated position does not permit such over-travel as tocause the curvatures of the bowed portions to become reversed. As willbe readily understood, the switch blade would then assume a stableposition with conductive buttons 64 in contact with abutment terminals78, 79, and would remain in that position even after the actuator headis subsequently retracted upwardly into its position of FIG. 2. Theswitch would then be inoperative for any future actuation. The provisionof tongue 58 in the present switch insures that such over-travel of theswitch blade cannot occur, regardless of any overrun of the actuatorhead 80 in its downward movement. Accordingly, in the operation of thepresent switch, retraction of actuator head 80 upwardly into its FIG. 2position relieves the stress theretofore imposed on tongue 58, andpermits the compressive stress in the lower leg 52 to tend to reduce thecurvature of that leg and thus to cause the conductive buttons 64 firstto slide upwardly on abutment terminals 78, 79, and, at some point inthe upward movement of actuator head 80, to cause the switch blade tosnap back into its rest position of FIG. 2.

As will be readily understood, by reason of the symmetry of the presentswitch, the same functions are being simultaneously performed byactuator nose 87 on the switch blade in the right hand side of FIGS. 2and 3.

Resilient means are provided for retracting the actuator head 80upwardly from its FIG. 3 position to its FIG. 2 position. In the presentillustrative embodiment of the invention, such means include a helicalspring indicated generally at 90, resting at its lower end on acylindrical support plate 92, and bearing at its upper end against anannular shoulder 94 ofa collar indicated generally at 95 which isreceived in a bore 96 formed in the lower face of actuator head 80.Support plate 92 is formed integrally with a fitting shank 91 embeddedin the center of base 24.

Immediately above actuator head 80 is a ball track guide indicatedgenerally at 100, which bears upwardly at its upper end against a stopplate 102 which in turn is in abutting contact at its upper face withthe annular bottom 104 of pushbutton carrier 22. An elongated metalsleeve indicated generally at has an annular shoulder 112 in its upperportion, against which stop plate 102 is seated, and the uppermost edge114 of sleeve 110 projects through a central aperture in bottom 104 ofpushbutton carrier 22, and is swaged or crimped outwardly as shown, inorder to retain sleeve 110, stop plate 102, and pushbutton carrier 22 infixed assembled relation.

Within sleeve 110 is an elongated tubular insulator indicated generallyat 120, having at its lower end an annular shoulder 122 supporting thelower end of sleeve 110. The tubular insulator is provided with an innerbore 123 throughout most of its length, defined upwardly by an annularshoulder 124, above which extends an internal bore 126 of reduceddiameter. A plug pin indicated generally at 130 is received in theinternal bore 126, and is provided at its lower end with an enlargedhead 132 seated against internal shoulder I24.

Within elongated bore 123 of tubular insulator 120 is provided resilientmeans in the form of helical spring 136, bearing at its upper end onhead I32 and seated at its lower end on the upper face 138 of a locatorstud indicated generally at 140 which is an integral extension offitting shank 91 and projects upwardly therefrom in slidable relationwith the internal bore 123 of insulator 120.

It will thus be seen that helical spring 136 serves to urge upwardly thetubular insulator 120 and, by means of the lower shoulder 122 of thatinsulator, the elongated sleeve 110 and stop plate 102 and pushbuttoncarrier 22 fixed to the sleeve 110.

Means are provided within boss 21 for limiting the upward movement ofthe parts just mentioned under the force of helical spring 136. Suchmeans hereinclude a tubular bushing indicated generally at 145 which isseated at its upper end against annular shoulder 146 of casing boss 21,and at its lower end abuts an internal annular shoulder 148 formedintegrally with body shell 32. In its upper portion, bushing 145 isprovided with a downwardly facing internal annular shoulder 149,againstwhich stop plate 102 abuts, thus limiting upward movement of thestop plate and the parts fixed thereto, including pushbutton carrier 22,elongated sleeve 114 and tubular insulator 120.

Latch means are provided in accordance with the invention for releasablyretaining actuator head 80 in its lower or actuated position of FIG. 3and 3a, regardless of the position of the pushbutton carrier 22 and theparts fixed thereto. Such latch means include the ball track guide 100previously mentioned, as well as a deis bounded laterally by shoulders160, 161 adjacent to the side edges of spring leg 156, thus forming ahousing groove for the leg to maintain it in vertical orientation asseen in FIG. 4. Leg 156 terminates downwardly in an enlarged plate 162,which overlies a generally rectangular window opening 164 formed in therecessed side wall 166 of bushing 145, in order to receive the outerspherical portion of detent ball 150. Leaf spring 154 is prestressed sothat plate 162 at the lower end of the leg resiliently biases ball 150leftwardly as seen in FIGS. 2 and 3. The ball is permitted lateralmovement by reason of the width of window 164, but is restrained againstvertical movement, other than slight mechanical clearance, by the upperand lower walls defining window 164.

The releasable latching means in accordance with the present inventioncontemplate that detent ball 150 will migrate around a generallyheartshaped or cardioid trackway, and means are incorporated in thetrackway for preventing migration of the ball in one direction, and thusinsuring that its migration occurs only in a predetermined desireddirection.

With reference to FIGS. 6a-d, the cardioid trackway is indicatedgenerally at 170 and is formed in a flat 172 provided in the otherwisecylindrical side wall of ball I guide bushing 100. Flat 172 is boundedlaterally by edges 174 and, as best seen in FIG. 8, the marginalportions of flat 172 adjacent to edges 174 are in slidable abuttingcontact with internalbosses' 175 formed in bushing 145. Ball guide 100is thus permitted vertical movement within the switch, but is restrainedby shoulders 175 against rotational movement.

The migration of detent ball 150 around cardioid trackway 170 will nowbe explained with particular reference to FIGS. 6a-d and FIG. 5, thelatter showing in developed form a profile of the trackway, including acomplete cycle in the migration of the detent ball. FIG. 6a shows theparts in their position when the switch is in its rest condition shownin FIG. 2, the ball 150 being in position A of FIG. 5. Upon depressionof pushbutton carrier 22, the vertically movable parts are forceddownwardly against the biasing force of retractor spring and internalhelical spring 136, and the parts will continue their downward movementto a position slightly lower than that shown in FIG. 3, with thelowermost shoulder 122 of tubular insulator bottoming against plate 180at the lower end of stud 140. During that downward movement, the detentball will migrate from its position of FIG. 6a to its position of FIG.6b. When downward pressure is now released from pushbutton carrier 22,all vertically movable parts will move upwardly under the force ofretractos spring 90 to the position seen in FIG. 3, and detent ball 150simultaneously moves to its position seen in FIG. 66, where it latchesthe ball guide 100 against further upward movement. However, thepushbutton carrier and the parts fixed thereto continue their upwardmovement under the force of internal helical spring 136 to theiruppermost positions seen in FIG. 3a.

The actuating parts remain in the actuated position of FIG. 3a until theuser again depresses pushbutton carrier 22 and its associated parts.Such depression moves all vertically movable parts to their lowermostintermediate position with shoulder 122 bottoming against plate 180, anddetent ball 150 simultaneously moving from its position of FIG. 60 toits position of FIG. 6d. Subsequent release of pressure on pushbuttoncarrier 22 permits the vertically movable parts to return to theirpositions seen in FIG. 2, and detent ball 150 simultaneously moves toits rest position seen in FIG. 6a.

The means in accordance with the invention for insuring that detent ball150 will migrate in the desired direction around cardioid pathway willbe best understood by reference to FIG. 5. As there shown, when ball 150is in its A position, it rests against a concave shoulder 185, extendingapproximately 90 of arc and having a radius of curvature substantiallyequal to the radius of ball 150. When now the switch is actuated by theusers depressing the pushbutton carrier 22, ball 150 moves along ramp186 to its intermediate B position corresponding to the bottoming of thevertically movable parts, and rests against concave shoulder 187.Release of force from the push button carrier will now cause the ball150 to move upwardly as seen in FIG. 5 along ramp 188 to its C position.In the latter position, ball 150 rests against concave shoulder I89.Subsequent depression of the pushbutton causes the ball to move alongramp 190 to its intermediate D position. where the ball rests againstconcave shoulder 191. Release of force from the push button now permitsball 150 to move upwardly as seen in FIG. 5 along ramp 192 to its Aposition. It is to be particularly noted that .the concave shoulders185, 187, 189, and 191 serve to prevent movement of ball 150 in theundesired direction, corresponding to downwardly in FIG. 5; the ball isinstead caused to move up the ramps as above described,

and thus performs a unidirectional migration around the cardioidtrackway 170.

In the embodiment of the invention thus far described and illustrated,the laterally extending blade arms 60 and 62 serve effectively as ashorting bar between corresponding terminals within the body of theswitch. Thus, in this form of the invention the electrical conductivityof the legs of the switch blade is not availed of, and such legs couldindeed be made of an electrically nonconductive material, provided thatsuch material had the necessary resilience to perform in the mannerhereinabove described and illustrated.

In an alternative form of the present invention,,the switch blade itselfis energized to constitute a common terminal of the switch, theelectrical conductivity of at least one leg of the switch thus beingimportant to the switch operation. Such a switch blade, and a switchassembly in which it is mounted, are shown in FIGS. 14-17 inclusive.

With reference first to FIG. 14, a switch blade indicated generally at250 includes an upper leg portion indicated generally at 254, comprisinglaterally spaced leg elements 257 and 259 separated by a central openportion 256. An actuating tongue 258 is formed integrally with the bladeand extends downwardly into the opening 256. Upper leg 254 terminatesupwardly in a narrowed projection 25] having an uppermost edge 255. Thelower ends of leg segments 257, 259 are merged in a laterally extendingyoke 260, and the blade includes a lower leg 252 extending downwardlyfrom yoke 260 and terminating in a lowermost edge 253. Central yokeportion 260 is provided on each of its faces with a conductive button,one of which is seen at 264 in FIG. 14. As will be evident, blade 250 issimilar in many respects to blade 50 previously described, the majordifference being that blade 250 does not include the laterallyprojecting arms 60, 62 of blade 50, and only one conductive button 264is provided on each of the faces of blade 250, rather than the two pairsof conductive buttons 64 on blade 50.

The mounting of blade 250 within the switch assembly, and its operationtherein, are substantially similar to the mounting and operation ofswitch blade 50 heretofore described, and will be understood in detailby reference to FIGS. 15, 16 and 17. Thus the upper pro jection 251 ofupper leg 254 is received in a V-shaped groove 72 formed in the lowerface 70 of dielectric body shell 32, identical to the correspondinglynumbered element in the form of the invention first described inconnection with FIG. 2. The lowermost edge 253 of switch blade 250 isreceived in a V-shaped notch 275 formed in a lower common conductiveterminal indicated generally at 280, embedded in a dielectric basemember indicated generally at 224. The distance between notch 72 andnotch 275 is less than the unstressed length of switch blade 250, and anabutment member 281 is disposed substantially midway of the overalllength of blade 250, whereby to impose on the blade oppositely bowedportions in its upper and lower legs. As seen in FIG. 15, andcorresponding to the lower right portion of FIG. 2, upper leg 254 has aconvex configuration, while lower leg 252 has a concave configuration,both terms being used from the viewpoint of the center of the switch. Onthe opposite side of yoke 260 from abutment member 281 is anotherabutment member 285, the abutment members 281 and 285 being normallyclosed and normally open abutment terminals 200 in respectively, andcommunicating downwardly with external normally closed terminal 282 andexternal normally open terminal 286 re spectively. In the upper portionof FIG. 15, actuator and its actuator nose 87 are identical inconstruction and operation to the correspondingly numbered elements inFIGS. 2 and 3. Thus, when actuator 80 is moved downwardly into itsactuated position in the construction shown in FIG. 15, it willslidingly contact tongue 258, whereby to move switch blade 250 to itsactuated position, not shown in FIG. 15, but corresponding to theposition of blade 50 seen in the lower right portion of FIGS. 3 and 3a.

As will be seen in FIG. 16, external normally closed and normally openterminals 282 and 286 respectively are desirably laterally offset fromcommon external terminal 280, to facilitate connecting leads to thoseterminals. Also, as best appears in FIG. 17, it will be seen that thepresent form of the invention, similarly to the form of the inventionfirst described and illustrated, contemplates the provision of a secondswitch blade and set of abutment terminals symmetrically disposed aboutthe center of the switch relative to the switch assembly thus fardescribed in connection with FIGS. 14, 15 and 16.

It is especially to be noted that the form of the invention shown anddescribed in connection with FIGS. 14l7 inclusive incorporates the sameadvantageous characteristic as the first form of the invention, in thatthe movement of actuator 80 and its nose 87 is in a direction generallyparallel to the general longitudinal axis of the switch blade. Moreover,contact between the actuator nose 87 and tongue 258 permits stress to bebuilt up in the upper leg 254 of the blade, and the amount of thatstress is virtually independent of the amount of overrun, if any, ofactuator 80 beyond its design limit of travel. By this arrangement, aspreviously described in detail in connection with FIGS. 2, 3 and 3a, theprovision of actuating tongue 258 eliminates the possibility that theswitch blade might completely reverse its configuration, with the upperbowed portion becoming concave, and the lower leg becoming convex. Asnoted previously, this would render the switch totally inoperative forsubsequent use, since those positions are stable and the switch wouldthus remain in that condition.

Modifications and changes from the illustrative forms of the inventionhereinabove described and illustrated are witihin the contemplation ofthe invention, and are intended to be embraced within the scope of theappended claims.

What is claimed is:

1. An electrical switch having a switch body with an internal cavity andprovided with upper and lower seats in the cavity, a switch blade ofresilient conductive sheet material having upper and lower end edgesreceived respectively in the upper and lower seats, the seats beingspaced closer together than the instressed distance between the bladeend edges, and a set of first and second fixed abutment means disposedon opposite sides of the blade substantially midway between the seats,the first abutment means being normally in abutting contact with oneface of the blade whereby to impose thereon a generally sinuous contourlongitudinally of the blade, the second abutment means being spacedslightly from the opposite face of the blade, characterized in that:

said blade includes upper convex and lower concave legs terminatingrespectively in said upper and lower end edges, the upper leg havingformed therein a central opening dividing said leg into a pair oflaterally spaced leg segments joined upwardly by a transverse yokeportion, and an actuatin g tongue formed integrally with the yoke andprojecting downwardly from the central portion thereof in lateralalignment with said opening and extending tangentially to the convexface of the upper leg;

and including actuator means movable toward actuated position along apath of movement substantially parallel to the plane joining said seatsand during said movement slidably flexing said tongue toward the centerof curvature of the upper convex leg whereby to create stress in theyoke and and upper leg tending to decrease the curvature of the upperleg and simultaneously increase the curvature of the lower leg, untilthe blade snaps out of contact with the first abutment means andintocontact with the second abutment means.

2. The invention as defined in claim 1 including releasable latch meansfor selectively retaining the actuator in actuating contact with thetongue.

3. The invention as defined in claim 1 wherein said switch includes asecond blade, a second pair of upper and lower seats, and a second setof first and second abutment means, all identical respectively to thefirst named corresponding elements and disposed within the cavitysymmetrically relative thereto, and said actuator means is disposedcentrally of the switch body and includes symmetrically placed portionsfor substantially simultaneously flexing the tongues of both bladesduring actuator movement toward actuated position.

4. The invention as defined in claim 1 wherein one of said seats isconductive and including a common terminal connected to the conductiveseat.

5. In an electrical switch, in combination:

a vertically oriented body of dielectric material having formed thereinan operating cavity having upper and lower walls, said walls havinghorizontally extending grooved seats formed therein;

a blade of generally cruciform shape and made of resilient conductivesheet material, including upper and lower legs terminating respectivelyin upper and lower parallel edges, and a pair of laterally extendingarms substantially midway between said edges,

the upper leg having formed therein a central opening dividing said leginto a pair of laterally spaced leg segments joined by an upper yoke,

and a tongue formed integrally with the yoke and extending downwardlytherefrom into said opening,

the distance between the blade upper and lower edges, when the blade isin unstressed planar shape, being greater than the distance between saidseats,

and the blade being supported by said body with its upper and loweredges in said upper and lower seats respectively;

a first pair of abutment terminals carried by the body in said cavityand abuttable against the outer portions of said arms, whereby to imposeon the blade an upper convex bow and a lower concave bow,

said tongue projecting tangentially to the upper convex bow;

a second pair of abutment terminals carried by the body in said cavityon the opposite side of the general plane of said blade from the firstnamed pair of abutment terminals and in general horizontal alignmenttherewith;

and a vertically movable actuator selectively movable between aretracted position above said tongue, and a lower actuated position andin slidable abutting contact with said tongue during at least theterminal portion of its downward movement,

whereby to flex the tongue toward the center of curvature of the upperconvex portion of the blade, and thereby to cause the switch to snapfrom its first position wherein said arms are in electrical contact withthe first named pair of terminals,

to a second or actuated position wherein said arms are in electricalcontact with said second pair of abutment terminals.

6. The invention as defined in claim 5 wherein said switch includesselectively releasable latching means for maintaining the actuator inits lower actuated position.

7. In an electrical switch having a switch body provided with a cavitytherein, a generally vertically oriented elongated blade consisting ofintegrally formed upper and lower legs of substantially equal length,and made of resilient conductive material, the blade leg ends beingmounted in seats in said body spaced closer together than the unstressedlength. of the blade, whereby to impose a longitudinal compressivestress on the blade, a pair of laterally spaced abutment means onopposite sides of the blade adjacent to the juncture of the legs, oneabutment means being in contact with the blade under rest conditions andimposing upper convex and lower concave bows on the legs, the provisionof:

and opening in the upper leg dividing said leg into a pair of spaced legsegments joined at their upper ends by a transverse yoke,

a tongue formed integrally with the yoke and projecting downwardlytherefrom and tangentially to the convex face of the upper leg,

and actuator means for selectively forcing the tongue toward the centerof curvature of the upper leg whereby to create stress in the yoke andupper leg tending to decrease the curvature of the upper leg until theblade snaps away from contact with said one abutment means into contactwith the other abutment means, the upper and lower legs retaining theirrespective convex and concave bowed configurations during movement ofthe actuator means.

8. The invention as defined in claim 7 wherein at least one of saidseats is conductive and including an external terminal connectedthereto.

9. The invention as defined in claim 8 including a second externalterminal connected to one of the abutments.

10. The invention as defined in claim 7 including releasable latchingmeans for selectively retaining said actuator in actuated position.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N 3,898,402Dated August 5, 1975 C Inventoflg) Anthony R. Ford It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

. I i In the grant (ONLY) insert columns 1, 2, 3 and 4, as shown on theattached sheets.

Signed and Sealed thls sixth D y of January 1976 [SEAL] Q Attest:

RU-TH C. MASON C. MARSHALL DANN Arresting Officer Commissioner ufParenlsand Trademarks FORM Po-1050 (10-69) UsCOMM-DC wave-Pas U.S. GOVERNMENTPRINTING OFFICE: 9

SNAP SWITCH WITH ACTUA'HNG TGNGL'E BACKGROUND AND SUhiMrUtr' OF THElNVENTlON The present in cntion relates generally to electricalswitches. and more particularly to a switch of the snap action typeemploying a switching blade of resilient conductive material which ismaintained under longitudinal compressive stress in the body ot theswitch whereby to impose on the blade oppositely bowed portions. whichmay for convenience he referred to as convex and concave bowed portions.

in a preferred form of the present invention. the resilient conductiveblade constituting the su itching element in the present switch isgenerally cruciform in shape. having upper and lower legs and a pair oflaterally cxtending arms substantially midway of the blade. The upperleg oi the blade is provided with a central Opening. and an integrallyformed tongue projects downwardly into the opening. When the blade ismounted in its houssng; seats. a pair oi abutment termirials abut thearms. and impose on the blade the oppositely bowed configurationmentioned above. A second pair of abutment terminals lies on theopposite side ol the arms from the first named pair. Actuation of theswitch consists ofdccreasing the curvature of the upper bowed portion ofthe blade and simultaneously increasing the curvature of the lowerportion of the blade until a point is reached when the blade snaps fromits rest position with its arms in contact with the first pair olabutment terminals into an actuated position with its arms in contactwith the second set of abutment terminals. Thus the arms constitute ashorting bar between the terminals of each pair. Actuation of the switchis effected by slid-able abutting Contact olan actuator element againstthe blade tongue, whereby stress is built up in the tongue and in theadjacent portions of the leg until the snap action results. Suchmovement of the tie-- tuator element is accomplished by depressing apushbutton in accordance with the present illustrative enibotliment ofthe invention.

In an alternative form of the invention. the blade arms are eliminated.one end of the blade is in electri cal contact with a common terminal.and one abutment terminal is provided on either side of the blade,approximately midway of its length. The blade is otherwise the same asthe cruciform blade lirst above mentioned. and includes anZttjltlitlltlg tongue in its upper leg.

Releasable latching means are desirably provided in accordance with thepresent invention. whereby a single depression ol" the pushbutton orotherwise actuating the actuator element. sen es to maintain the switchin its actuated condition until a second depression of the actuator. anda lkzll dt-tt-nt clement i"--.lllt;tli}. receiwd in pt sitioi'is ol theactuating: t'ltniicnt. lln' il-li lt v'riy ii aylt cm y rtr ilient.

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is suitable contoured and provided with ramps to insure that the balldetent. which is permitted limited lateral movement relative to thetraclzway in order to follow the cardioid pa h. proceeds always in thesame direction around said path.

in the preterrt-cl form ofthe invention. a second blade and associatedabutment terminals may be provided. disposed symmetrically to the firstabout It central vertical axis of the switch. so that movement of theactuator switches two separate circuits substantially simultaneously.

it is accordingly a principal object of the present invention to provideand disclose an electrical switch havi g a novel conductive blade toaccomplish the switching. and releasable latching means to maintain theswitch. scle tively. in either its make or brcal; position. Otherobjects and purposes are to provide. in such a switch, a blade orgenerally cruciform shape. having a pair of laterally extending armsconstituting in effect a shorting bar. to provide. in such a blade, anupper leg having an opening formed therein and an integral tongueextending downwardly into the opening. slidably abuttable by an actuatorclement during actuatitm: to provide a releasable latching means toselectively maintain the actuator element in actuated position. andincluding a cardioid tracliway having. upper and lower lock positions.in which a ball detent is resiliently biused (or travel around thecardioid between one lock position and the other; for providing in sucha switch a duplicate set of switching elements and terminals by which todouble the circuit handling capacity of the switch in compact space; andfor other and additional objects as will become clear from a reading ofthe lol lowing description of a preferred embodiment oithe invention,taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWlNGS FlG. l is a side clevational view of aswitch embodying the present invention.

HO. 2 is a vertical sectional vie taken on line llll ofl lG. 1. showingthe parts in their normal or rest positions.

HG. 3 is a fragmentary sectional view similar to H6. 2, except showingthe parts in their actuated positions.

llG. 3A is a fragmentary sectional view similar to FIG. 3 and laterallyaligned therewith. showing the right hand portion of the switch properin actuated position as in l-l-Zj. 3. but with the pushbutton carrierretracted to its rest position.

HO. 4 is a sectional view taken on the line lV-l\/ oi FIG. 2.

H0. 5 is a developed view of the trackway and, in dotted outline. thesuccessiye positions of the ball detcnt therein.

FlGS. (m.!1.canddare successive views of the migration of tin: balldetent around the cztrdioid trackway'. H0. (in corresponding to theposition of the switch seen in l-'l(i. 2. Hi (ncorrcs ondin to theposition of the switch seen in i ti. 3. and HUS. n!) and fut slime hithe ball and trackway' in intermediate positions.

l" (i.-2, 7. 8 and ill trc sectional \lt h taken along: the arrows \'ll--\'ll. \llll \'lll. and iv respectively of l-l(i. 2.

l-lt'} i :1 sectional view taken on the arrows l.\' ---lX (it Hi 3,

FIG. ll is a bottom plan view ol the switch taken on the arrows Xl-Xl olFIG. 2.

FIG. I2 is a perspective view oi the preferred form of blade inaccordance with the invention.

FIG. 13 is a schematic diagram showing the wiring of the severalterminals of the preferred embodiment of the invention.

FIG. I4 is a perspective view of a switch blade in accordance with analternative form of the invention.

FIG. 15 is a fragmentary sectional view of a portion of a switchincorporating, the blade of FIG. 14.

FIG 16 is a fragmentary sectional view taken on the arrows XVl--X\/l ofFIG. 15.

FIG. 17 is a fragmentary sectional view tal-zcn on the arrows XVli-XVIIol FIG. 15. and showing the operative portions of the switch in thclet'tportion ol the switch assembly, including a second blade and pair ofterminals, disposed symmetrically relative to the corresponding parts inthe right hall of the. switch assembly.

DETAILED DESCRIP'IION Referring now to the drawing, in FIG. I there isindicated generally at 20 a housing for Z'ontaining the operativeportions of the present switch. the housing 20 being desirably made ofmetal and including an integrally; formed externally threaded boss 21projecting upwardly from the housing propsr. for convenience in mountingthe present switch hr rsing on a c ntrol panel or the like. A pushhuttoncarrier 22 is telescopically received within the threaded bore 2! andextends thereabove, and is adapted to have a suitable pushbutton mountedon its upper end for actuation by the user. With continued reference toTIC. 1, tin. lower portion of the cylindrical wall of the housing 2 iscrimped in wardly at 23, in order to be attached to a downwardlyextending base 24 ol dielectric material, from which outlet terminalsproject downwardly. there being visible in FIG. 1 a total of four suchterminals, arranged in pairs '25, 26 and 27, 2-3, As will be laterunderstood in detail, and as a glance at FIG. I! will show, there aredesirably a total of eight downwardly projecting outlet terminalsdisposed symmetrically about a central vertical plane of the switch, theother four terminals being designated by primed reference numerals.

The internal construction of the elements of the switch will be bestunderstood by reference first to FlGS. 2 and 4-, showing those parts intheir normal or rest positions.

Thus the lower portion of housing 20 comprises a hollow cylindricalcasing indicated generally at 30 which receives in its upper portion abody shell of dielectric material indicated generally at 32. This shellincludes an uppc r annular ring; portion 3-4 and, extend-- ingdownwardly therefrmn and integrally formed therewith, a pair ofarcuatcly extending sldrts 3s. 37 (see FIG. 4), interrupted by a pair oldiametrically opposed openings 3?! 3), seen in ll i, 2. 'l be lowerinterrupted annular edges we or Slill'iS an, 37 a ut the upper face 41ol dielcclric base member 24. .-\t lll\' midpoint olarcuate skirts 3-!"and 37, body shell 52 is provided with support columrc-z 4?. and -llrcs'icctivcly, having coaxial posts -14 and 45 which extend downiurdlyinto bores 46 and 47 l'orrncd in dielectric base 34.

As will be later utnlctstood. alter assembly of the switch blades withshe l AP. art-i l-iiwc .54, the lowermost ends 4;"; and -55" ol post"l-l and -35 .li'i l'.:.-.n seated or welded to llLllLlt'Clll portionsol' dielectric base 24. so

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Pa e 3 that the shell and base form an integral dielectric bodycontaining therewithin the operative portions of the switch, includingswitch blades and abutment terminals to be now described.

In FIG. 12 there is indicated generally at 50 the preferred form ofblade constituting the moving contact member in accordance with thepresent invention. Blade 50 is of generally cruciform shape, having anelongated lower leg 52 terminating downwardly in a lower edge 53 and anupper leg indicated generally at 54 terminating in an upper edge 55which is parallel to lower edge 53. Upper leg 54 is of substantiallygreater width than that of lower leg 52, and has formed therein acentral opening 56 between a pair of laterally spaced leg segments 57and 59 joined by an upper transverse yoke. An integrally formed tongue58 extends downwardly from the yoke, into the opening 56 with itssidewalls spaced inwardly from the inner walls of leg seg ments 57 and5). so that, as will be later understood, tongue 58 can be flexed awayfrom the plane of the yoke during operation. The blade also includes apair of arms 60, 62. extending laterally substantially midway betweenlower and upper edges 53, 55. The total cross sectional area ol legsegments 57 and 59 is approximately equal to that of lower leg 52.

All of the elements of blade 50 thusl ar described are integrally formedofa flexible conductive material such as a sheet of copper or copperalloy. To minimize contact resistance during switch operation, as iscustomary in the switch art, cont-actor buttons 64 may be provided onthe arms, desirably made of any of well known materials ofhighconductivity such a silver alloy or the like. As sh wn in FIG. .2, theouter surfaces of the contactor button 64 are desirable slightly convex.

There will now be described in connection with FIG, 2 a switch assemblycomprising the blade of FIG. 12. its mounting in the dielectric bodywithin casing 30, and the abutment terminals with which the blade armsmake contact during switch operation. As will be evident from FIG. 2,the presentillustrative embodiment of the invention includes a pair ofidentical switch assemblies, disposed precisely symmetrically relativeto a central vertical plane through the switch. and for brevity only theswitching assembly in the left portion of FIG. 2 will be described indetail. Thus the body shell 32. and base 24, both of dielectricmaterial, define therebetween an operating cavity housing the switchblade 50 and the terminals with which the switch arms are abuttable. Thelower face of body shell 32 has formed therein a groove 72, and base 24of the dielectric body similarly has a groove 74 formed therein.

Each groove constitutes a seat for receiving the lower and upper edges53, 55 of blade 50, and the longitudinal spacing between grooves 72 and74 is appreciably less than the distance or height between the edges 53and S5 of the blade when the blade is in its unstressed planar conditionseen in FIG. 12. Blade 50 is thus l'orccd to assume u curvedconfiguration throughout its length, and a pair of abutment terminals 76and 7'7 (compare HG. l l) serve to impose upon blade Si) an oppositelybowedconfiguration in the upper portion of blade 50 comprising leg 54from the bowed conligtxrtv lion in the lower portion othladc 5t)comprising. leg 2. More specifically. and using the terms from theviewpoint oi the central portion of tluswitch, upper leg 54 ir-sinncs itconverts curvature. while lower leg 53. assumes a concave curvature.lndcr thcsc conditions

1. An electrical switch having a switch body with an internal cavity andprovided with upper and lower seats in the cavity, a switch blade ofresilient conductive sheet material having upper and lower end edgesreceived respectively in the upper and lower seats, the seats beingspaced closer together than the instressed distance between the bladeend edges, and a set of first and second fixed abutment means disposedon opposite sides of the blade substantially midway between the seats,the first abutment means being normally in abutting contact with oneface of the blade whereby to impose thereon a generally sinuous contourlongitudinally of the blade, the second abutment means being spacedslightly from the opposite face of the blade, characterized in that:said blade includes upper convex and lower concave legs terminatingrespectively in said upper and lower end edges, the upper leg havingformed therein a central opening dividing said leg into a pair oflaterally spaced leg segments joined upwardly by a transverse yokeportion, and an actuating tongue formed integrally with the yoke andprojecting downwardly from the central portion thereof in lateralalignment with said opening and extending tangentially to the convexface of the upper leg; and including actuator means movable towardactuated position along a path of movement substantially parallel to theplane joining said seats and during said movement slidably flexing saidtongue toward the center of curvature of the upper convex leg whereby tocreate stress in the yoke and and upper leg tending to decrease thecurvature of the upper leg and simultaneously increase the curvature ofthe lower leg, until the blade snaps out of contact with the firstabutment means and into contact with the second abutment means.
 2. Theinvention as defined in claim 1 including releasable latch means forselectively retaining the actuator in actuating contact with the tongue.3. The invention as defined in claim 1 wherein said switch includes asecond blade, a second pair of upper and lower seats, and a second setof first and second abutment means, all identical respectively to thefirst named corresponding elements and disposed within the cavitysymmetrically relative thereto, and said actuator means is disposedcentrally of the switch body and includes symmetrically placed portionsfor substantially simultaneously flexing the tongues of both bladesduring actuator movement toward actuated position.
 4. The invention asdefined in claim 1 wherein one of said seats is conductive and includinga common terminal connected to the conductive seat.
 5. In an electricalswitch, in combination: a vertically oriented body of dielectricmaterial having formed therein an operating cavity having upper andlower walls, said walls having horizontally extending grooved seatsformed therein; a blade of generally cruciform shape and made ofresilient conductive sheet material, including upper and lower legsterminating respectively in upper and lower parallel edges, and a pairof laterally extending arms substantially midway between said edges, theupper leg having formed therein a central opening dividing said leg intoa pair of laterally spaced leg segments joined by an upper yoke, and atongue formed integrally with the yoke and extending downwardlytherefrom into said opening, the distance between the blade upper andlower edges, when the blade is in unstressed planar shape, being greaterthan the distance between said seats, and the blade being supported bysaid body with its upper and lower edges in said upper and lower seatsrespectively; a first pair of abutment terminals carried by the body insaid cavity and abuttable against the outer portions of said arms,whereby to impose on the blade an upper convex bow and a lower concavebow, said tongue projecting tangentially to tHe upper convex bow; asecond pair of abutment terminals carried by the body in said cavity onthe opposite side of the general plane of said blade from the firstnamed pair of abutment terminals and in general horizontal alignmenttherewith; and a vertically movable actuator selectively movable betweena retracted position above said tongue, and a lower actuated positionand in slidable abutting contact with said tongue during at least theterminal portion of its downward movement, whereby to flex the tonguetoward the center of curvature of the upper convex portion of the blade,and thereby to cause the switch to snap from its first position whereinsaid arms are in electrical contact with the first named pair ofterminals, to a second or actuated position wherein said arms are inelectrical contact with said second pair of abutment terminals.
 6. Theinvention as defined in claim 5 wherein said switch includes selectivelyreleasable latching means for maintaining the actuator in its loweractuated position.
 7. In an electrical switch having a switch bodyprovided with a cavity therein, a generally vertically orientedelongated blade consisting of integrally formed upper and lower legs ofsubstantially equal length, and made of resilient conductive material,the blade leg ends being mounted in seats in said body spaced closertogether than the unstressed length of the blade, whereby to impose alongitudinal compressive stress on the blade, a pair of laterally spacedabutment means on opposite sides of the blade adjacent to the junctureof the legs, one abutment means being in contact with the blade underrest conditions and imposing upper convex and lower concave bows on thelegs, the provision of: and opening in the upper leg dividing said leginto a pair of spaced leg segments joined at their upper ends by atransverse yoke, a tongue formed integrally with the yoke and projectingdownwardly therefrom and tangentially to the convex face of the upperleg, and actuator means for selectively forcing the tongue toward thecenter of curvature of the upper leg whereby to create stress in theyoke and upper leg tending to decrease the curvature of the upper leguntil the blade snaps away from contact with said one abutment meansinto contact with the other abutment means, the upper and lower legsretaining their respective convex and concave bowed configurationsduring movement of the actuator means.
 8. The invention as defined inclaim 7 wherein at least one of said seats is conductive and includingan external terminal connected thereto.
 9. The invention as defined inclaim 8 including a second external terminal connected to one of theabutments.
 10. The invention as defined in claim 7 including releasablelatching means for selectively retaining said actuator in actuatedposition.